Hydraulically actuated stop for a hydraulic ram unit



May 6, 1969 HYDRAULICALLY ACTUATED STOP FOR A HYDRAULIC RAM UNIT FiledAug. 21, i967 INVENTOF? GUY L. DANIELS, DECEASED BY HERBERT H. PETERS,ADMINISTRATOR G. DANIELS 3,442,178

United States Patent 3,442,178 HYDRAULICALLY ACTUATED STOP FOR AHYDRAULIC RAM UNIT Guy L. Daniels, deceased, late of Franksville, Wis.,by Herbert H. Peters, administrator, Wauwatosa, Wis., assignor to J. I.Case Company, Racine, Wis., a corporation of Wisconsin Filed Aug. 21,1967, Ser. No. 662,197 Int. Cl. F15b 13/042, 15/22; F01b 11/02 US. Cl.91-403 Claims ABSTRACT OF THE DISCLOSURE A hydraulically actuated stopfor a hydraulic ram unit including a cylinder with a piston movable in achamber defined by the cylinder. Fluid passageways exist in oppositeends of the cylinder, and a valve is operative intermediate one of thepassageways and the cylinder chamber for closing off the passageway andthereby creating an increase in fluid pressure on one side of a pistonslidable in the chamber. The increased fluid pressure limits the strokeof the piston, as desired. The valve is located in a bore which providesflow communication between the one passageway and the cylinder chamber,and the valve responds to pressure in a compartment on one side of thevalve, and this fluid pressure causes the valve to close the onepassageway, as desired.

This invention relates to a hydraulically actuated stop for a hydraulicram unit. More particularly, it relates to a hydraulic ram unit whichhas means associated therewith for effecting the stop of the piston inthe unit.

Different constructions for providing a hydraulically responsive stopfor a rain unit are already known. The prior art includes constructionswhich are in the nature of valves which are responsive to the movementand position of the piston to create hydraulic pressure on the valve andthereby effect the stop. However, these prior constructions are complexin both their arrangements and operations, and they commonly havespecial parts and constructions extending exteriorly of the cylinderwhich forms a part of the ram unit. Also, it is common to have theseprior constructions arranged with the stop or limit valve disposed in amanner such that both sides of the valve are in the fluid-flowpassageway of the cylinder so that the stop itself is governed by thefluid pressure on opposite sides of the valve as determined by thepressure applied to the cylinder rather than by the control of the valveindependent of a passage of fluid through the cylinder. In part, thismeans that the prior constructions cannot be selectively set to regulatethe stopping of the piston at any desired posiion, and it also meansthat the piston cannot over-run a selected stop position.

Accordingly, it is a general object of this invention to improve uponthe aforementioned prior construction. This object is accomplished bythe provision of a ram unit with a hydraulically actuated stop which iscompletely contained within the cylinder of the unit, does not requireany external parts, is not responsive to or dependent upon fluid flow onboth sides of a control valve utilized in the stop means, and isrelatively simple in its manufacture and function so that it is feasibleto provide it and is reliable in its operation.

Another object of this invention is to provide a hydraulically actuatedstop for a ram unit, wherein the stop provides a greater range overwhich it can be set as compared to the range of the constructionsheretofore known. This object of course includes the arrangement whereinthe stop can be readily and easily selectively set for stopping thepiston in a selected position. Also in- 3,442,178 Patented May 6, 1969cluded in this object is the fact that the selected set position can bemaintained over repeated strokes of the piston so that the piston willcome to the same position in successive strokes.

Still another object of this invention is to provide a hydraulicallyactuated stop for a ram unit and wherein the selectively set stop in theunit can be selectively overrun to permit the piston to go beyond theset stop position, but, nevertheless, the construction is also soarranged that on subsequent strokes of the piston, the selected stopposition can be achieved, if desired, without requiring any adjustmentof the unit.

Other objects and advantages will become apparent upon reading thefollowing description in light of the accompanying drawings, wherein:

FIG. 1 is a longitudinal sectional view through a hydraulic ram unitincorporating this invention.

FIG. 2 is an enlarged sectional view taken on the line 2-2 of FIG. 1.

FIG. 3 is a longitudinal sectional view similar to FIG. 1 but showingonly a fragment of the unit and showing a modification thereof.

The hydraulic ram unit of this invention can of course be used inpower-lift hydraulic cylinders, and it is commonly used with a controlvalve which is connected to the unit by means of fluid tubes or pipesand which is constructed to control the flow of fluid to the unit inaccordance with actual pressures within the cylinder of the unit. Thisis a type of valve commonly known in the art to be a spring-centeredspool valve which has a plurality of fluid ports and wherein the spoolis movable to selectively open and close the ports through manual orautomatic, that is fluid pressure responsive, control means. Thiscommonly known spool type valve is also of the pressure-operated detentrelease type. Further, it is conventionally arranged such that when thepressure of the fluid increases in the valve, then the spoolautomatically sets itself to lock the valve in that position. This is ofcourse what will therefore lock the further flow of fluid to the ramunit and thus the piston is locked or stopped in its position. If onedesires further description and disclosure of this type of combinedspool valve and ram unit, and description of the valve itself, referencemay be had to US. Patent No. 2,765,746.

The drawings show the ram unit, which includes the hydraulic cylinder 10and the piston 11 disposed therein for the usual reciprocation in thecylinder chamber 12. The cylinder also has the fluid ports orpassageways 13 and 14 which permit the ingress and egress of hydraulicfluid with respect to the chamber 12. It will of course also beunderstood that the ram unit may be of the double acting type so thateither port 13 or 14 can be the inlet or outlet port. The cylinder ofcourse also has the end caps 16 and 17 which are fluid tight with thecylindrical portion designated 18 of the cylinder 10 generally. The cap17 shows a boss 19 having an opening 21 for mounting one end of the uniton any pin so that the end would of course be anchored as desired.Further, the piston 11 has a hollow piston rod 22 and a clevis 23 isshown attached to the end of the rod 22 which extends through thecylinder end cap 16. The clevis 23 can of course be attached to a pin orthe like so that the opposite ends of the cylinder 10 are conventionallyattached for the wellknown purposes.

Of course the piston rod 22 is attached to the piston 11 to reciprocatetherewith, and the rod has a hollow interior 24. A spool 26 is shownwith an elongated end 27 disposed within the piston rod opening 24. Theother end of the spool 26 is designated 28 and is enlarged and serves asa valve which is more fully described and explained later. A rod 29 isdisposed slidably within a hollow interior designated 30 within thespool 26.

At this point it will therefore be observed that when for instance thepiston 11 moves from right to left, the position it is now in in FIG. 1,in the cylinder chamber 12, the clevis wall 31 abuts the end of the rod29 to slide the latter within spool 26. Thus any fluid in the spoolsinterior 30, and in a compartment designated 32, will have its pressureincreased. It will now be understood that when the pressure on the face33 of the spool 26, which face 33 is on the left side of the spool 26,becomes greater than the pressure on the right side or face of the spool26, the spool will move to the right, say from the position that it isshown in in FIG. 1. This pressure differential causes the spool 26 tomove over the annulus 34 formed in the end cap 17 and in fluid-flowcommunication with the passageway 14, as shown. The spool end 28 is ofcourse cylindrical and is snug within the cylindrical bore 35 in the endcap 17. The spool end 28 thus acts as a valve with respect to thepassageway 14 and of course stops the full flow of fluid from thechamber 12 and in front of the advancing piston 11. Thus itwould ofcourse be assumed in that description that the passageway 13 was theinlet of the fluid and the passage way 14 was the outlet so that thepiston 11 moves from right to left in FIG. 1 to the position in which itis shown. Further, it is of course the blocking of the passageway 14 bythe valve 28 that creates the pressure differential on the oppositefaces of the spool 26, and this causes the valve 28 to retain its closedposition with respect to the passageway 14.

It will then also be understood that when the pressure difl'erential iscreated by the movement of the rod 29 in what is described as thecompartment 32, then the pressure differential is initiated and thepassageway 14 is closed off. The spool valve (not shown) then beingconnected to the passageways 13 and 14 senses the increase in pressurein the chamber 12 on the side of the passageway 13. This causes thespool valve to respond to this pressure increase and center itself tolock the spool in a position where no further fluid entcrs the chamber12 and this of course effects the hydraulic stop of this invention.

It will of course be understood that the remote valve mentioned has amanual control, like that shown in the referenced patent, so thatpressure could continue to be applied through the passageway 13 todisplace the piston 11 beyond a set stop position even though the valveportion 28 of the spool 26 is over the passageway 14. This is true sincethe valve 28 has no fluid seal between the chamber 12 and the passageway14 so that fluid can actually leak or be forced past the valve 28 andout the passageway 14. This therefore means that the piston 11 can gopast a selected stop position by simply holding the manual controlhandle of the spool valve which is not shown. Further, even after thisdesired over-running of the stop position, the next stroke of the piston11 could be stopped at the selected position if the control handle isnot manually held as described. This is a feature of this particularconstruction. It will of course be noticed that the end cap 17 has aseal 36 which surrounds the spool end 28 on the left of the passagewayor annulus 34 and thus fluids cannot leak out of the compartment 32.

A threaded plug-type member 37 threadedly adjustably extends into theend cap 17 and has its inner end 38 snugly received in an opening 39 inthe end cap 17. A passageway 41 communicates with the opening 3 9 andwith the compartment 32 to actually therefore be a part of thecompartment 32 as well as the spool interior 30* is a part of thecompartment 32 for this purpose. Thus it will then be apparent thatmoving the plug 37 in or out with respect to the end cap 17 will affectthe pressure of the fluid in the compartment 32 and will thereby affectthe action of the valve 28. In this manner, the construction is arrangedto provide adjustability so that the piston 11 can be stopped at anydesired point along 4 its stroke. A fluid seal 40 prevents the fluidfrom leaking past the plug 37 and out of the compartment 32.

A needle valve 42 is threadedly disposed in the end cap 17 and iseffective between a passageway 43, which is in part a portion of thecompartment 32 and is in communication therewith and a passageway 44which extends to the annulus 34. It will therefore be seen that thecompartment 32 can be charged in the amount of fluid therein simply byopening the valve 42 and introducing fluid through the passageway 14 andinto the compartment 32. The plug 37 could be retracted to a limit whichmay be defined by a stop 46 while the compartment 32 is being filled.Then closing the valve 42 would seal the compartment 32 again.

It will of course be understood that the passageway 14 could be used asthe inlet to introduce the fluid into the chamber 12 at the face of thepiston 11 and move the piston to the right from the position it is in inFIG. 1. This can even be accomplished when the valve 28 is over thepassageway 14 since it will be recalled that adequate fluid pressure canbe provided to have the fluid leak past the valve 28 and into the bore35 which is open to the chamber 12. FIG. 3 shows another embodiment ofthe construction for the purpose of a double acting hydraulic unit. Inthis instance, a ball check valve 47 is disposed in a passageway 48extending between a passageway 49 and the chamber 12. Thus pressurecoming into the passageway 14 and the passageway 49 will pass the ballcheck 47 and move into the chamber 12. A spring 51 is shown behind theball 47 to normally urge it in a closed or seated position in thepassageway 48.

Also, a compression spring 52 is disposed between a wall 53 of the valve28 and a snap ring 54 in the cylinder end cap 17. Thus the spring 52normally urges the spool 26 to the left when such movement is desired.Of course the pressure differential created by fluid on opposite facesof the spool 26 overcomes the pressure of the spring 52 to move thespool 26 to the right as described.

Adequate fluid seals are provided on the construction between the movingparts described. Thus the piston seal 56 extends around the piston 11and a seal 57 extends around the rod 29. Likewise, a seal 58 extendsaround the piston rod 22, and seals 53 extend around the needle valves42. These seals are shown to be of the O-ring type which is well known.

It will therefore be understood that the valve 28 and its seal 36 aresuch that a minimum pressure can be retained in the compartment 32. Thispressure of fluid is adequate to move the spool 26' to the right andclose on the passageway 14. However, the fluid may still be forced pastthe valve 28 from the chamber 12 and into the passageway 14 so that thepiston 11 can over-run the set stop as described. This is thereforesaying that the closing ability of the valve 28 is less on the rightside of the valve than it is on the left side as viewed in the drawings.However, the valve is capable of adequate closing with respect to thepassageway 14 for sufficiently sealing therewith to displace the spool26 and create the pressure in the chamber 12 and the passageway 13 foractuating the one unshown spool valve and effect the hydraulic stopdesired.

With regard to the feature of leaking past the valve 28, it will ofcourse be understood that plug 37 can be set in a desired position toeffect the proper stop.

What is claimed is:

1. A hydraulically actuated stop for a hydraulic ram unit, comprising ahydraulic cylinder having a fluid passageway at each end thereof andhaving an intermediate chamber, a piston fluid-tightly and slidablydisposed in said chamber, a piston rod attached to said piston andfluid-tightly extending through one end of said cylinder to the exteriorthereof, said cylinder having a bore fluidflow communicating one of saidpassageways and said chamber at the other end of said cylinder, a valveslidably disposed in said bore and being operative on said one of saidpassageways and being fluid-flow exposed to said chamber on the side ofsaid valve toward said one end of said cylinder, a fluid compartment insaid bore fluid-flow isolated from said passageways and beingfluidtightly sealed from said chamber by said valve on the operativeside of said valve opposite from said chamber for actuation of saidvalve in response to a minimum fluid pressure in said compartment toclose said valve on said one of said passageways, said valve having acylindrical opening defining a part of said compartment, and a plungerin said cylindrical opening and movable by abutment of one of saidpiston and piston rod therewith and operative on said compartment forcreating said minimum fluid pressure in response to the movement of saidpiston.

2. The subject matter claimed in claim 1, wherein said valve is arrangedwith seal means to fluid-tightly seal said compartment from saidchamber, said valve being sufficiently loose in said bore to befluid-seal related to said bore to provide for fluid sealing betweensaid chambe: and said one of said passageways only at a fluid pressurelower than said minimum fluid pressure in said compartment when saidvalve is in a closed position on said one of said passageways.

3'. The subject matter claimed in claim 1, wherein said valve and saidcompartment are within said cylinder and co-axial therewith forperformance in direct response to axial movement of said piston rod insaid cylinder.

4. The subject matter claimed in claim 1, including a valved passagewayextending between said compartment and said chamber for selectiveintroduction of fluid into said compartment and from said chamber.

5. The subject matter of claim 1, wherein said rod is axially hollow andsaid valve cylindrical opening is coaxial with said hollow rod, and saidplunger is axially movable in said rod.

References Cited UNITED STATES PATENTS 1,902,018 3/1933 Davis 91403 X2,456,236 12/1948 Acton 9l--403 2,587,182 2/1952 Livers 91404 2,615,43010/1952 Fletcher et a] 91406 2,973,744 3/1961 Hennells 91-26 3,024,7703/1962 All-bright 9l403 3,054,383 9/1962' Hanna 9124 FOREIGN PATENTS629,109 4/ 1936 Germany.

MARTIN -P. SCHWADRON, Primary Examiner. I. C. COHEN, Assistant Examiner.

US. Cl. X.R.

